Apparatus for purifying exhaust gases of internal combustion engines



Feb. 7, 1967 A. A. ZIMMER 3,303,003 APPARATUS FOR PURIFYING EXHAUSTGASES OF INTERNAL COMBUSTION ENGINES Filed March 11, 1963 \AuTo EXAUSTINTAKE MANIFOLD VACUUM INVENTOR AUSTIN A. ZIMMER AGENT United StatesPatent 3,303 003 APPARATUS FOR PURIF YING EXHAUST GASES OF INTERNALCOMBUSTION ENGINES Austin A. Zimmer, Elkridge, Md., assignor to W. R.

Grace & o., New York, N.Y., a corporation of Connecticut Filed Mar. 11,1963, Ser. No. 264,133 4 Claims. (Cl. 23-288) This application is acontinuation-in-part of my earlier filed copendin g application Ser. No.204,399, filed June 22, 1962, and now abandoned.

This invention relates to an auto exhaust system. In particular thisinvention is directed to a novel process and combination of apparatusfor automatically controlling the temperature of a catalytic exhaustpurifier.

According to this invention, the automatic temperature control of thecatalytic exhaust purifier is obtained by utilization of an air pumppivotally mounted on an automotive engine and connected to a pumpactuating means and a temperature sensing and valve means associatedwith the exhaust purifier. In response to a signal from the temperaturesensing means, a valve means associated therewith will open and permitair from the manifold section of the engine to flow through a conduit tothe pump actuating means. The pump actuating means will then cause theair pump to pivot about a hinged connection, which varies the pitchdiameter of the pump pulley and causes the pump to operate at anincreased speed and to force additional air through the catalyticpurifier. In this way, the temperature of the catalytic exhaust systemcan be automatically adjusted to compensate for deviation from a desiredtemperature.

The problem of air pollution is not a new one. However, the problem hasbeen aggrevated in many cities in recent years. The air in most citiescontains substantial quantities of both oxides of nitrogen and theproducts of incomplete combustion of organic fuels.

In the presence of sunlight, photolysis of the oxides of nitrogen leadsto the formation of measurable quantitics of ozone. The ozone, in turn,reacts with various organic pollutants to form compounds which can causethe many undesirable manifestations of smog, such as eye irritations,visibility reduction and plant damage.

When meteorological conditions prevent the rapid dispersion ofpollutants, a smog condition results. Furthermore, it is now known thatin many cities a major portion of organic pollutants is derived fromunburned or partially burned gasoline in auto exhausts.

Another pollutant of much concern is carbon monoxide which isundesirable because of its toxic nature. This too is derived mainly fromauto exhaust emissions.

Almost since the advent of the automobile, attempts have been made tosolve the problem by rending harmless and unobjectionable the noxiousfumes which are the by-products of internal combustion engines. Variousdevices and filters using elementary catalytic materials, and from the1920s on various modifications of filters and mufflers, have beendesigned in an attempt to solve this problem. To date, none of them havemet with success complete enough for practical application. One of themost difiicult problems to overcome is the fact that although a givenpurification system Works well after the motor is warmed, the initialactivity of the catalyst is too low.

Closely related to this problem is the problem that the process of myinvention is designed to solve. That is, the problem that once thecatalyst is warmed up to operating temperatures and the motor is idling,at idle speeds the motor is producing large quantities of hydrocarbonsand carbon monoxide. Under idle conditions of automobile operation thecatalyst temperature rises rapidly because of the exothermic'heat of thecatalytic reaction. Severe damage to the catalyst and its container canresult under these circumstances.

Several investigators have realized that the only practical way to treatfumes to reduce hydrocarbon and and carbon monoxide pollution is tooxidize the hydrocarbons to carbon dioxide and water and oxidize thecarbon monoxide to carbon dioxide.

A wide selection of oxidation catalysts have been produced in the pastvarying in both chemical composition and physical structure. Withrespect to chemical composition, the ability of a wide variety of metalsand metal oxides, either alone or in combinations, to catalyze thecomplete oxidation of hydrocarbons has been noted. To be sufficientlyeflicient for the removal of hydrocarbons and carbon monoxide from autoexhaust gases and to meet the standards of maximum emission currentlyunder consideration in legislatures of various states, a catalyst fortreating exhaust gases must become efiicient within a few minutes afterengine startup and must maintain its activity throughout the variousmodes of engine operation. A catalytic converter must maintain itscatalytic activity for a period of not less than one year and preferablytwo years or approximately 20,000 miles of engine operation.

A particularly difiicult problem is the problem occasioned by theoperation of the automobile for short runs and operation of the engineat idling speeds. It has been found that after the catalyst has beenwarmed up and the engine speed is then reduced to idle, that excessiveheat is generated in the catalytic converter. The reason for thiscondition is obvious. The catalyst has been warmed up to the temperatureat which it is most efiicient and at idling speeds the amount of carbonmonoxide and hydrocarbons is increased. Thus, the catalyst is convertinga larger quantity of both hydrocarbons and carbon monoxide at a timewhen it is at its peak efiiciency. The conversion takes place veryrapidly and the exothermic heat from the reaction causes the temperatureof the catalyst bed to increase.

It is well known that catalytic reactions in automobile exhaust systemsare generally exothermic and temperature control of the catalyst isrequired in order that the temperatures do not reach the point where thecatalyst or the container or both would be damaged in any way. The usualmethod of operation is to use various control mechanisms to eitherdivert the exhaust :gases away from the catalyst or to cool the gases bysurface heat transfer methods.

It is known that the problem of excessive heating of .a catalyticmufiler while the engine is operating at idling speeds can be controlledby passing additional quantities of excess air through the mufllerduring such periods of operation. (See Patent Number 3,045,422.)According to such process the catalyst temperature is controlled byvarying the amount of air passing over the catalyst bed from the amounttheoretically necessary to eflect conversion of the carbon monoxide andhydrocarbons to an amount in excess of this theoretical quantity. Thisexcess air will remove heat from the chemical reaction and therebycontrol the temperature Within the rnufiler. This principle is wellknown and does not form a specific part of this invention.

The devices which are known for implementing the above prior art processattempt to control the catalyst temperature by providing for apredetermined amount of air to be admitted to the rnuflier from aconstant speed air blower through a valve opening in response to certainaccelerator positions or muffler back pressures or pressure drops. Thedisadvantage with these devices is that, although all of these devicesrelate to the catalyst tem perature, they are not directly affected bythe catalyst 3 temperature, nor consequently reactive to sudden orunscheduled different catalyst temperatures than those theoreticallycontemplated.

It is an object of this invention, therefore, to provide a process and acombination of apparatus whereby the above mentioned problems of theprior art are overcome. It is an additional object of this invention toprovide a novel process and a combination of apparatus for automaticallycontrolling the temperature of a catalytic exhaust system. Otherobjects, advantages, and features of this invention will be apparent tothose skilled in the art in view of the following more detaileddescription of the invention.

These and other objects are achieved by means of this invention in whichan air pump pivotally mounted on an internal combustion engine is usedin combination with a pump actuating means and a temperature sensing andvalve means associated with a catalytic exhaust purifier. According tothis invention, the temperature within the exhaust purifier is measured,a valve means associated with the temperature sensing element is openedin response to a temperature reading which exceeds a predeterminedvalue, and the speed of the air pump is then simultaneously adjusted bypivoting the air pump about a hinged connection, thereby varying thepitch diameter of the pump pulley and adjusting the speed of the pump.This increase in the speed of the air pump causes the pump to forceadditional amounts of air through the muffler. As a result, thetemperature within the muffler will be decreased back to that desired.

The invention will be further understood by referring to theaccompanying drawing. It should be understood that this drawing isintended to be only a means of illustrating the inventive concept and isnot to be considered a limitation of same.

In the drawing, the numeral 1 designates a standard type of automotivemuffler with an exhaust inlet 9 and outlet 10. The muffler contained aconventional, commercially available exhaust oxidation catalyst. Atemperature sensing element 12 is positioned within the muffler. Athree-way valve 13 is associated with the temperature sensing elementand is positioned within a conduit '6 which connects the manifoldsection of an internal combustion engine with a pump actuating means 4.In this embodiment, the pump actuating means is comprised of a pair ofvacuum diaphragms and is connected to the base of the air pump 2. Theair pump 2 is also one of standard construction and is capable of beingdriven at varying speeds of operation. The air pump is pivotallyconnected at 3 to the automotive engine. The pump is driven by means ofa belt and pulley arrangement comprised of a variable pitch, springloaded sheave pulley 5 which is attached directly to the air pump and asecond pulley 7 mounted on the automobile fan. A flexible =hoseconnection 8 carries the air from the pump 2 back to the inlet to thecatalytic muffler 9.

The process of this invention operates as follows. The air pump 2provides the air necessary for the normal operation of the catalyticconverter. The air is mixed with the exhaust gases from the enginemanifold which move through the pipe to the catalytic mufller. As thegases are converted they pass out through the exit of the mufller 10. Asthe temperature within the muffler exceeds the pre-determined desiredtemperature (generally, approximately 1200 F.), the temperature sensingelement 12 will open the three-way valve 13 thereby'connecting the pumpactuating means 4 with the manifold of the internal combustion engine.The actuating means will actuate the air pump 2 by pivoting the pumpabout the hinged connection 3. This will cause the pump to move to thealternate position shown in the broken line on the drawing, therebyvarying the pitch diameter of the pump pulley and increasing the speedof the pump. The increased speed of the pump increased the air output ofthe pump and concomitantly the amount of air which is passing throughthe catalytic mufiler 1. This increase in the amount of air, i.e., theexcess in the amount of air theoretically required for conversion ofcarbon monoxide and hydrocarbons, will return the temperature within themother to the desired temperature within a relatively short period oftime. When the temperature within the mufller has returned to thedesired temperature, the sensing element 12 will close the valve 13,thereby actuating the pump actuating means 4 to return the air pump 2 toits normal position. When the pump 2 has returned to its usual positionthe air output is decreased and the volume of air passing to the mufllerthrough flexible connection 8 and the inlet 9 will also be decreased.

The above described operation of this invention will occur automaticallywhen the automobile engine is operating at idle speeds, for it is atthese speeds that the temperature within the muffler will increase. Ingeneral,

it is desired to maintain the temperature within the muf- Example I Themagnitude of the problem was illustrated in a series of runs in which anautomobile was operated at a speed of 3050 miles per hour over thehighway and the temperature in the catalyst bed measured. After severalminutes of operation the automobile was stopped. The engine was sloweddown to idle. The data collected in one of these runs is shown in TableI:

TABLE I Time in Speed Temperature Minutes in m.p.l1. of Exhaust Gases inF.

0 50 960 3 50 860 6 50 910 9 30 850 12 Idle 950 15 Idle 1, 010 18 Idle1, 21 Idle 1, 310 24 Idle 1, 400

It is apparent from an examination of these data that a temperatureincrease of about 500 F. takes place when the automobile is operated atidle after being operated at a speed of about 50 miles an hour. Thetemperature rise took place in this particular instance over a period of12 minutes.

The air was being fed to the catalyst bed at the rate of 3.5 cubic feetper minute during this run.

Example I II The combination of apparatus described in this inventionwas installed on a standard eight cylinder automobile. The automobilewas driven at a speed of approximately 50 miles per hour for severalmiles. The automobile was then brought to a stop and the enginepermitted to idle (an air pump speed of approximately 600 r.p.m.). Atthe beginning of the idle cycle, the air pump output was approximately 4cubic feet per minute. After 1 /2 minutes the catalyst temperature hadrisen from 1010 F. to over 1200 F. The temperature sensing elementopened the three way valve thereby establishing communication betweenthe manifold of the engine and the pump actuating means. The pumpactuating means then activated the air pump, causing the pump to pivotabout its hinged connection to the engine and operate at an increasedspeed (1500 r.p.m.). The output of the air pump when oper ating at thisspeed was between and 11 cubic feed per minute. of approximately 1540 F.had been reached. This temperature was then reduced to 1400 F. in 1 /2minutes and further lowered to 1200 F. during an additional 4 /2 minutesof operation. After this time, the temperature was held substantiallyconstant at approximately 1200" F. by the automatic control action.

The data from this example is shown in Table H.

TABLE II Time in Speed in Air Flow Temperature Minutes m.p.h. in c.1'.m.of Catalyst Bed in F.

0 Idle 4 1, 010 1% Idle 4 1, 280 3 Idle 4 1, 540 4% Idle 10 1, 400 6Idle 10 1, 360 7% Idle 10 1, 300 9 Idle 10 1, 220 10% Idle 10 1, 210 12Idle 10 1,190 13% Idle 4 1, 200 15 Idle 10 1, 210

An analysis of the exhaust gases was made at both the high and low airflows (4 cubic feet per minute and 10 cubic feet per minute). Theconversion was found to be approximately 91% for the carbon monoxide and86% for the hydrocarbons. The efiect of the conversion when changing theair flow from 4 to 10 cubic feet per minute was found to be negligible.Thus, it is apparent that decreasing the temperature of the catalyst bythe use of excess air has no deleterious effect on the function of thecatalyst.

Many modifications and variations of the invention herein set forth maybe made without a departure from the essence and scope of the invention.This invention is intended to cover all methods and combinations ofapparatus in which a sensing device placed in the catalyst mufilerdirectly controls the admission of air to the muf- At the end of threeminutes, a peak temperaturev fler through a direct connection means,such as pressure, vacuum, or electricity, between the sensing device andthe means for controlling the air delivery to the muffier. Only suchlimitations as indicated in the appendant claims should be applied tothis invention.

I claim:

1. A combination of apparatus for automatically controlling thetemperature of a catalytic exhaust purifier comprising,

(a) means for purifying exhaust gases including a housing containing anoxidation catalyst,

(b) inlet and outlet openings within said purifying means for theexhaust gases to enter and exit therefrom,

(c) a temperature sensing means positioned Within said purifying means,

(d) valve means associated with said sensing means and positioned withina conduit connecting a manifold section of an internal combustion enginewith a pump actuating means connected to a variable speed belt drivenspring loaded air pump pivotally attached to said engine,

(e) and a second conduit connecting said pump means with said exhaustinlet opening.

2. The combination of claim 1 in which the pump actuating meanscomprises a pair of vacuum diaphragms.

3. The combination of claim 2 wherein the air pump is belt-driventhrough a spring loaded, variable pitch sheave pulley.

4. The combination of claim 3 wherein the valve means is a three-wayvalve and is regulated so as to open when the temperature within thepurifier exceeds 1200 F.

References Cited by the Examiner UNITED STATES PATENTS 2,743,529 5/1956Hayes 23288 X 3,065,595 11/1962 Gary 232 X 3,172,738 3/.19-65 Houdry23288 X OSCAR R. VERTIZ, Primary Examiner.

EARL C. THOMAS, Examiner.

1. A COMBINATION OF APPARATUS FOR AUTOMATICALLY CONTROLLING THETEMPERATURE OF A CATALYTIC EXHAUST PURIFIER COMPRISING, (A) MEANS FORPURIFYING EXHAUST GASES INCLUDING A HOUSING CONTAINING AN OXIDATIONCATALYST, (B) INLET AND OUTLET OPENINGS WITHIN SAID PURIFYING MEANS FORTHE EXHAUST GASES TO ENTER AND EXIT THEREFROM, (C) A TEMPERATURE SENSINGMEANS POSITIONED WITHIN SAID PURIFYING MEANS, (D) VALVE MEANS ASSOCIATEDWITH SAID SENSING MEANS AND POSITIONED WITHIN A CONDUIT CONNECTING AMANIFOLD SECTION OF AN INTERNAL COMBUSTION ENGINE WITH A PUMP ACTUATINGMEANS CONNECTED TO A VARIABLE SPEED BELT DRIVEN SPRING LOADED AIR PUMPPIVOTALLY ATTACHED TO SAID ENGINE, (E) AND A SECOND CONDUIT CONNECTINGSAID PUMP MEANS WITH SAID EXHAUST INLET OPENING.